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Infinity's Reference Series amplifiers offer impressive power and extensive controls for fine-tuning your sound  an ideal way to boost your music's intensity and clarity. Strict reliability testing results in durable, dependable amplifiers, and their compact size gives you more installation options in tight places.

The heavy-hitting Infinity Reference 475a 4-channel amplifier sends 75 watts RMS to each of your front and rear speakers. Or, you can bridge the amp to 2-channel mode, and pump out 360 watts total to your two subs. And every Infinity Reference amplifier is certified to deliver power as advertised.

The variable frequency filters and adjustable bass boost let you contour the amp's output to suit your speakers or subs for more efficient output and cleaner low-end kick. Preamp outputs simplify hookup to another amp in your system, so system building is quick and easy. Direct-connect terminals make reliable connections without need for any crimping or soldering.

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Product Research

Features

CEA-2006 Compliant: CEA-2006 is a new system of testing and
measurement methods for mobile audio amplifiers. This voluntary standard advocates
a uniform method for determining an amplifier's RMS power output and signal-to-noise
ratio. The criteria for measuring power uses a DC input voltage of 14.4 volts and
the RMS power output is measured into a 4-ohm load, with 1% or less Total Harmonic
Distortion (THD) plus noise, and at a frequency range of 20 Hz to 200 Hz, when
applicable. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA)
at a reference of 1 watt into 4 ohms. CEA-2006 allows consumers to compare car
amplifiers and receivers on an equal basis. The Infinity Reference 475a under
CEA-2006 regulations is rated at 74 Watts RMS x 4 channels with a 85dBA signal
to noise ratio.

Bridgeable: In addition to powering 4 full-range speakers, the
Reference 4-channel amplifier can be bridged and configured in a 3-channel or 2-channel
application. The amplifier is rated at 180 Watts x 2 at 4 ohm in 2-channel mode and 75
Watts x 2, 180 Watts x 1 at 4 ohm in 3-channel mode.

Line Level Inputs: The front and rear channels of the amplifier each
have separate line-level RCA inputs with independent gain (Input Sensitivity) controls.
The Input Sensitivity controls will accept an input signal of 100mV to 6.0 Volts. If you
are using a receiver with only one pair of preamp outputs you will need to use two RCA
Y-adapters. When using a Y-adapter, fader controls will be lost.

Protection Circuitry: The amp features 4-way protection, and will
shut itself down in the following cases:

DC Output: DC voltage is detected on
the amplifier output

Temperature: Amplifier is overheated

Over/Under Voltage: Voltage at the
+12V (Battery) terminal is less than 8.5V or more than
16V

Short Circuit: Short circuit in speaker
or speaker wire

Power and Protection LEDs: The amplifier features a Power and
Protection LED on top of the unit. The Power LED illuminates Green when the amplifier
is supplied power. The Protection LED will illuminate Red when the amplifier goes
into protect-mode.

Controls

Application Selectors: There
is an application selector for the front and rear
channels that allow you to select which channels
of the amplifier drive your front or rear speakers
and what channels drive your subwoofers. There is
also a stereo and mono (left or right) switch for
each channel of the amplifier if you want a mono
signal from either the front or rear channel.

Front and Rear Input Levels:
Individual rotary controls for the front and rear
channels of the amplifier used to match the level
of the preamp input signal.

Crossovers: The 475a has built-in high pass and low pass
crossovers for the front and rear channels. The high pass and low pass crossover's
slope are 12 dB/octave and are continuously variable from 32Hz to 320Hz and can be
controlled independently for the front and rear channels. The amplifier can
also be operated at full-range simultaneously for both front and rear channels.

Crossover Mode Switches: Individual
slide switches for the front and rear channels used to
select Low-Pass, High-Pass or Full-Range configuration.

Crossover Frequencies: Independent
rotary controls for the front and rear channels to set
the cutoff frequency of the Low or High Pass Filter
between 32 and 320 Hz.

Bass Boost: The Bass Boost control allows you to enhance the
bass output of your system at 50Hz up to 6dB independently for the front and rear
channels.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to
find elsewhere. That's because we have our own in-house Product Research
team. They verify what’s in the box, check the owner's manual, and record
dimensions, features and specs. We stay on top of new products and technologies
to help people make informed choices.

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By checking this box you agree your review becomes the property of Crutchfield,
that you are over 18 years of age, that you own or have owned this product, and
that you are located within the United States or its territories. Please see our
Review Guidelines for more information. We reserve the right (but are not
obligated to) review all submissions and edit or remove any review in any manner
which we deem necessary. Your review should be posted within seven days.

Trash in less than 6 months

Written By John B., Overland Park, KS on Saturday, February 28, 2015

Amp was installed along with Infinity speakers, Infinity BassLink, and Kenwood head unit by professional shop. All equipment purchased from Crutchfield. Less than 4 months after install, amp stuck in Protect mode and utterly useless. Glad to see it's discontinued. Speakers and other equipment still work well. Infinity amps, at the very least, should be avoided. Laughably, Infinity will assess $15 restocking fee for lack of original packaging. If you take the plunge, make sure you have ample warehouse space available to maintain all boxes, etc.

At least Crutchfield service is more consumer-minded than the dopes at Infinity, and proactively processed an equipment exchange.

The one star rating was earned by Infinity, whereas Crutchfield gets an A.

Pros:If used as a paperweight, paperwork will surely be secure. Also, worked as an amplifier spectacularly...for only four months and change.

Cons:Died after less than 5 months. Junk. Will avoid entire Infinity line as a result of this defective unit.

Rocks my Jeep!

Great sounding Amp; Make sure you have room to install, the amp is a large amp and it requires lots of airflow to keep it cool. I have it on a Kenwood eXcelon 997 deck, Infinity speakers (frnt and rear) and a JL 8 sub with its own amp. HairNation never sounded so GOOD!

Infinity Reference 475a

Got this amp to run pair of kicker cs components in front door and kicker cs 6.75 in rear door amp works great run gain all the on down on full range sounds great don't run hot and for the price can't beat it had in for lil over a month now. And it hooked up to factory 14 tacoma Hradec run in to tacotunes recurve sounds fantastic

Great Amp!

This is a fantastic amplifier! So much clean power! I've got it hooked up to a Pioneer deck with 4V pre-outs. My speakers are Polk DB 5.25 components. I have the amp gain only at 25% and the speakers get killer loud and retain crisp sound clarity. I got this amp when it was on sale, so I could not ask for more for the price.

Pros:Powerful, clean, affordable

Cons:It's an older model amp and with that comes a larger size. I had plenty of room, so this wasn't an issue for me, but if you have a small mounting space you should consider looking at newer more compact amps.

INFINITY REFERENCE 475A

I kept my stock head unit since it has an excellent tuner in it. One of my original speakers was blown. However adding this amplifier to a complete set of 4 6.5" Infinity reference component speakers has created fantastic sounds in my Avalanche. The Infinity speakers are rated to handle 90 rms peak and the unit puts out 75 rms so it's as perfect as you'll get. The clarity, as well as bass and highs is excellent. Thank you Crutchfield for a great price on a great product.

Runs HOT. Does not last long.

Purchased this amp with the advice from a sales associate. It runs hot so have it in an open area. I was only able to get 2 1/2 years out of it tops before issues. It went into protect mode on and off. I called to see what it could be I was advised that its probably the speakers. So I purchased all new speakers. Wasn't the speakers it was the Amp.. I have an old Sony amp pushing my sub that's way over 15yrs old and it still works. So maybe $100 per year is what's expected.

Pros:Produces good sharp sound

Cons:Can not depend on it working. Check reviews elsewhere. Lots of issues .

Great Amp

THIS AMP ROCKS. 5 Channels, so I hooked a component set (6 1/2 door & Tweets) + Rear (Infinity 6 1/4) and the 5th channel I hooked a tear shaped box with 4 POLK 6x9 Woofers in it. All sounds exactly how I imagined... but better

Infinity 475a - a solid choice

Written By Daniel, Atlanta, GA on Friday, June 21, 2013

A very solid amplifier with good sound quality, and plenty of power. It pushes my polk db 6.5" component's and infinity 6x9's to their limits. I've had the 475a for 4 years now! This is the only amplifier I've had to not quit on me (mostly class D subwoofer amp's like the alpine mrp-350, mrp-1000; great amps, but gave out...). For me, the volume is at it's limit, or else I'm not listening to music haha. The Infinity 475a should be on anyone's list if they are looking for a cheaper alternative that will last, all the while sounding great!

bang for your buck

Written By hoff33, columbus ohio on Wednesday, April 11, 2012

I recently purchased this amplifier to replace my kicker zx650·4. I expected a considerable decrease in sound quality. But I think this amplifier sounds just as good for half the price...very nice amp.

Infinity Reference 475a

I purchased this for my son's 96 Ford Contour with 4 6x8 Kenwood speakers in the doors. We had previously installed a Kenwood headunit and b4 the amp it sounded pretty good. After installation I was absolutely blown away! I couldn't have imagined how good this small system was going to sound. Highs are clear and loud and the bass is difficult to believe unless you hear it firsthand. My 17 yr old son decided to not install a sub! It's only been running 3 weeks but no problems whatsoever and astounding performance.

Good sound, bad quality

Written By rnd, Boston, MA on Tuesday, April 20, 2010

I had this mounted in the trunk with lots of open space around it for a cool air supply. Never abused, this amp lasted 7 months when the front right channel went out (same as another reviewer here...). It performed well up until then. I have always thought Infinity's products were very good for their price point. This one was a disappointment.

Great Amp

I bought this amp to power my Infinity referance 5030 and 5032 it rocks those speakers!! my music is loud and clear love infinity. My father said they where some of the best and he was right.
Pros:
Really loud and clear
Con:
I have alot of Static through them and a hummm
Have been trouble shooting and i think i got it

Best customer service on difficult sale

The quality of customer service is not measured during the smooth sales nearly as much as it is with the difficult sales. I bought this amp from Norm, who had sold me other equip. I was going to get Crutchfield to install. Upon review by the installer, Devon, he found that he was going to have to do some extensive electrical surgery that was not in Crutchfield's database. I appreciated explanation, and return of the amp was cheerfully accommodated. I was impressed with the trouble Norm & Devon went to try to figure an easy way to make the install work, but, in the end, it wasn't worth the tradeoffs I would have had to make. Thanks, guys, and I will definitely buy from you again!

Clear and powerful

Just got say this amp is awesome. It's powers my 6.5" component polk audio dbs very clearly. I can turn it up real loud without distortion. This is my first amp i bought. Never thought my car would sound so much clearer and that loud.

Pros: Dirt cheap 75wx4 at 4 ohms. I probably can turn it all the way, but don't want to blow out my ears. Also its alot smaller than my sub amp. it's heavy, but looks nice and built to last.

Cons: People say it gets hot, it does, but it never shuts down on me. I don't know, but i had to switch around the patch cables a little. I dont know which one was that fault the radio or amp. No biggie Crutchfield helped me out.

I would reccomend it to my friends and family.

Also I want to say to Crutchfield. Thank you for helping me out with my purchase. You guys are the best.

Going the Distance...

Installed in a 2004 Jeep Rubicon, with a soft top, an audiophiles nightmare, but...BUT, this amp has made the inside of this jeep more like an amphitheater. Great purchase, excellent reco by Stephen, and an A+++ for the overall experience.

Keep Looking

I got the fist amp and right before the year warr. went out it blew sent it to infinity and it was a nightmare they said they were going to replace it with a new amp. and i waited and waited and waited it took 8 weeks to get the amp. you can not talk to a person at infinity unless you want to buy now i got the new amp. and the front right channle is gone....I have alpine, Boston Ac.,and have never had this many problems.

You get more than you pay for

Written By quisp, Los Angeles, CA on Saturday, October 18, 2008

I got this amp to go with a set of Kappa 62.9i's. I got it figuring that I should probably amp up the 4 main 6.5" speakers if I am going to put in a 500 watt sub. I have to say that the output is pretty impressive and I would not be surprised if it was slightly higher than 90 watts/channel. The ampere rating on this amplifier is 70 amps max and it does get quite hot, but it sounds amazing none-the-less. This is is much better than it's price would indicate less than half of what I got the JL 500/1 for and is a much more important part of my system as a whole. BUY this AMP

Awesome Amp

Written By Kyle, Malone, New York on Friday, October 10, 2008

I bought this amp to go with a set of infinity kappa 50.7cs component speakers and a set of infinity kappa 693.7i 6x9s. This amp combined with the inifinity speakers puts out very crisp highs and great mids. I can't say much for the lows, due to the fact that the speakers have crossovers that cut off much of the low-end audio; which is good as long as you have a sub. What the speakers do put out for lows is absolutely crisp up to the highest levels. Mine also tends to get very hot, so hot in some cases that I can't keep my hand on it, but it keeps on pumping out the volume, and doesn't seem to affect performance. I'm absolutely satisfied with this amp, especially for the price. I'm giving it four stars out of five only because the trim piece that you have to take off to mount the amp would not stay on for me, so I ended up taking it completely off. Probably due to the fact that I have it mounted right next to a subwoofer on the seat back of my Buick, but still it shouldn't vibrate off. Regardless of the trim falling off, I would not hesitate to buy this amp or any Infinity speaker!!

Infinity Reference 475a

Infinity Reference 475a

Written By Kyle, Portland, ME / Manchester, NH on Saturday, December 15, 2007

Bought the Infinity Reference 475a to go along with the Kappa 60.7cs and Kappa 693.7 (90 Watts to each) and I am very Impressed with the clarity and volume of the speakers and the job the amp is doing powering them. I listen to my music pretty loud and I really only use about 50% of the power this system is capable of putting out, maybe 60% if I'm feeling brave. The Highs sound awesome, the mids sound awesome and the lows are reasonable as well (if you crave bass you'll need a woofer regardless) but the lows do sound good. I really cant say anything bad about this... Mine does get very hot though... anyone else experience this? I know there is good air circulation the way it is mounted and the space in my trunk...

Awesome Amp

I just added this amp to push 4 each PIONEER TS-A6881R. I am very impress with the power this amp supplies. The amp and speakers make a good combination to provide a loud, clear and crisp sound. The speakers scream "power". Along with a MTX 500 watt amp, 2 each Eclipse 10 in. woofers and a JVC KW-AVX800 DVD Receiver , this is a awesome sounding sound system for my 07 Ford 4-door Lariat. My only complaint is the amp was too thick to mount behind my back seat with the other amp. I had to mount it under the passenger seat, which meant re-locating my tire jack. But that was a minor obstacle easly overcome. I would definitly recommend this amp to someone.

Happy

Written By Wil, Orlando, FL on Sunday, June 17, 2007

I am very happy with this amp, I just installed in my toy/tac/4dr/lb it is pushing infinity 6020 comp and kappa 62.7i they sound great. Easy to adjust, very clean, crisp and it looks cool at night. It also is a mangaible size.